Composition

ABSTRACT

The present invention provides a composition comprising: i) at least one compound of formula (I): 
                         
wherein R 1  and R 2  are independently selected from a group consisting of hydrogen, unsubstituted or substituted C 1-19  hydrocarbyl or a group of formula (II):
 
                         
wherein Q is a bond or an unsubstituted or substituted hydrocarbyl group; wherein R 3  is selected from a group consisting of hydrogen and unsubstituted or substituted C 1-18  hydrocarbyl; wherein the R 1 —C—R 2  backbone is from 5 to 20 atoms in length; wherein each A and B is independently an unsubstituted or substituted unsaturated cyclic hydrocarbyl group; and wherein n is an integer from 0 to 10; and ii) a diluent or carrier; wherein the compound(s) of formula (I) is present in an amount sufficient to provide, at −30° C., at least 1 wt % of iron, based on the weight of the composition.

The present invention relates to a composition. In particular thepresent invention relates to a composition which may be used in theregeneration of particulate filter systems which receive exhaust gasesfrom a combustion system.

Diesel particulate emissions are perceived as a health problem. Onesolution to this problem is to filter the carbonaceous material fromexhaust gas. Devices capable of doing this are well known. Such filtersmust be periodically regenerated by combustion of the carbonaceousdeposits. The effect which iron-organic compounds, particularlyferrocene and derivatives thereof, have in promoting combustion is knownboth with respect to open flame combustion as well as combustion inengines. Furthermore, the prior art (e.g. Fuels 1999, 2^(nd)International Colloquium, 20-21 Jan. 1999 at Esslingen TechnicalAcademy) discloses that diesel particulate filters (DPFs) can beregenerated by additives in diesel fuel since the products of combustionto which the additive gives rise reduce the ignition temperature of thesoot particles which have been filtered out in the diesel particulatefilter (DPF), these latter particles igniting and burning away.

Since iron-organic compounds, such as ferrocene, in solid form are notideal for dosing to the fuel, dosing may be conveniently carried outusing readily diesel-soluble and fully diesel-compatible solutions ofthe compounds or one or more iron-organic compound(s) that are liquid atthe temperature of use. It is desirable, particularly when thecombustion system is located on a vehicle, for any solutions containingthe iron-organic compounds to be highly concentrated solutions so thatthe additive supply container can be as small as possible in size, or,rather, does not need to be frequently topped up.

Ferrocene itself has a solubility limit of 2.4% by weight at −40° C.corresponding to an iron content of 0.72% by weight in a highly aromaticsolvent (PLUTOsol™ APF, supplied by Octel Deutschland GmbH). In anon-aromatic solvent (Isopar L) ferrocene provides an iron content ofonly 0.22% by weight at −30° C. Solutions of iron-organic compounds withan iron content of more than 1.0% by weight, preferably more than 2.5%by weight and more preferably more than 4.0% by weight at −40° C. aresought. Preferred solvents are low-aromatic or non-aromatic solventsincluding the Isopar™ range as this allows a wider selection ofmaterials, in particular polymers, especially HDPE, to be used in theconstruction of the additive supply container and pumping/deliverysystem.

HDPE is a low-cost widely-used material, which is not normallycompatible with highly aromatic solvents. Where aromatic solvents areused in HDPE additive supply containers, distortion or swelling of thecontainers may occur, such that physical changes and degradation can beexpected. These aspects are not compatible with the necessary 12-15 yearlife of the container. Furthermore, aromatic solvents may permeate thewalls of an HDPE container, such that solvent is lost over timeresulting in increased solution viscosity and undesirable changes in thecharacteristics of the additive formulation.

Concentration effects due to solvent loss may lead to an increase iniron-organic compound content, thus altering the active content of irontreated to the fuel. This may affect the regeneration process and maylead to excessive exothermic heat of reaction inside the DPF duringregeneration. Ceramic DPF materials may be adversely affected, resultingin cracking or other damage from thermal shock. Furthermore, ashaccumulation, which is a natural process eventually requiring thewashing out of the filter, may accelerate where an excessive iron treatrate results from solvent loss induced concentration effects.

HDPE containers can be modified to increase their compatibility witharomatic solvents. The process involves forming a barrier or lininginside the container in order to prevent swelling and distortion of thecontainer and loss of solvent by permeation through the walls. Asuitable barrier or lining can be provided by a process calledco-extrusion, where containers are fabricated by blow-moulding. Wherecontainers are made by injection moulding, a barrier can be created bypost-manufacture fluorination. Co-extrusion with a polyamide layer, orfluorination to level 5 after injection moulding are techniques wellknown to those skilled in the art.

There are significant disadvantages to the prior art methods of adaptingHDPE containers to allow the storage of additives formulated witharomatic solvents. The need to provide a barrier to prevent solvent lossby permeation, and also to prevent swelling and distortion which wouldotherwise occur when storing aromatic solvents in HDPE containersimposes a significant cost penalty on the storage of an additiveformulated with an aromatic solvent. Similarly, there is a penalty inmanufacturing logistics incurred by the need to fluorinate containersafter injection moulding, or alternatively a lack of flexibilityincurred by the need to co-extrude a barrier liner with HDPE in a blowmoulding process. A further disadvantage of HDPE containers which havebeen adapted to increase compatibility with aromatic solvent is thatthey are more difficult to recycle than containers consisting solely ofor consisting mainly of HDPE. It is becoming increasingly important forvehicle components to be easily recycled as in the future vehicles willbe recycled at the end of their useful life-time. It is thereforegreatly preferred to formulate an additive with a low-aromatic ornon-aromatic solvent to reduce costs, eliminate manufacturing logisticsproblems and avoid recycling problems.

The present invention alleviates the problems of the prior art.

In one aspect the present invention provides a composition comprising:i) at least one compound of formula (I):

wherein R₁ and R₂ are independently selected from a group consisting ofhydrogen, unsubstituted or substituted C₁₋₁₉ hydrocarbyl or a group offormula (II):

wherein Q is a bond or an unsubstituted or substituted hydrocarbylgroup; wherein R₃ is selected from a group consisting of hydrogen andunsubstituted or substituted C₁₋₁₈ hydrocarbyl; wherein the R₁—C—R₂backbone is from 5 to 20 atoms in length; wherein each A and B isindependently an unsubstituted or substituted unsaturated cyclichydrocarbyl group; and wherein n is an integer from 0 to 10; and ii) adiluent or carrier; wherein the compound(s) of formula (I) is present inan amount sufficient to provide, at −30° C., at least 1 wt % of iron,based on the weight of the composition.

In one aspect the present invention provides a fuel additive dosingapparatus comprising a supply container formed from a plastics materialincompatible with an aromatic diluent or carrier and a compositioncontained within the supply container comprising: i) at least onecompound of formula (I):

wherein R₁ and R₂ are independently selected from a group consisting ofhydrogen, unsubstituted or substituted C₁₋₁₉ hydrocarbyl or a group offormula (II):

wherein Q is a bond or an unsubstituted or substituted hydrocarbylgroup; wherein R₃ is selected from a group consisting of hydrogen andunsubstituted or substituted C₁₋₁₈ hydrocarbyl; wherein the R₁—C—R₂backbone is from 5 to 20 atoms in length; wherein each A and B isindependently an unsubstituted or substituted unsaturated cyclichydrocarbyl group; and wherein n is an integer from 0 to 10; and ii) alow aromatic or non-aromatic diluent or carrier.

In one aspect the present invention provides a fuel compositioncomprising (a) a fuel; and (b) a compound of formula (I):

wherein R₁ and R₂ are independently selected from a group consisting ofhydrogen, unsubstituted or substituted C₁₋₁₉ hydrocarbyl or a group offormula (II):

wherein Q is a bond or an unsubstituted or substituted hydrocarbylgroup; wherein R₃ is selected from a group consisting of hydrogen andunsubstituted or substituted C₁₋₁₈ hydrocarbyl; wherein the R₁—C—R₂backbone is from 5 to 20 atoms in length; wherein each A and B isindependently an unsubstituted or substituted unsaturated cyclichydrocarbyl group; and wherein n is an integer from 0 to 10.

In one aspect the present invention provides a method of regenerating aparticulate filter located in an exhaust system of a combustion systemfor fuel, which comprises contacting carbon-based particulates, presentin the particulate filter, with combustion products of a composition asherein defined.

In one aspect the present invention provides use of a composition asherein defined for decreasing the regeneration temperature of aparticulate filter located in the exhaust system of a combustion system.

It has been found that compounds of the present invention advantageouslyhave a high degree of solubility or dispersibility, preferablysolubility, in the diluent or carrier present in the compositionaccording to the present invention. Additionally, the composition of theinvention advantageously has temperature stability across a widetemperature range. In particular, no stability problems should resultwithin the range of from −30° C. to +90° C., and preferably within therange of from −40° C. to +90° C. It has surprisingly been shown that thecomposition of the present invention may provide a composition having aniron content of up to 10 wt %, which is stable down to −30° C., andpartially stable down to −40° C. and beyond. Further, it has been foundthat such solutions containing 2.5 wt % iron are stable at −40° C.

A further advantage of the present invention is the provision ofcompositions the viscosity of which is not too greatly increased withinthe low temperature range. This could otherwise have adverse effectsupon the pumpability of the composition and could, for example, resultin difficulties in conjunction with a metering pump. In this connection,the viscosity of the composition according to the present invention,having an iron content of 2.5% by weight, is advantageously less than,or approximately equal to, 25 mPas at a temperature of −40° C.

The term “hydrocarbyl” as used herein relates to a group comprising atleast C and H. If the hydrocarbyl group comprises more than one C thenthose carbons need not necessarily be linked to each other. For example,at least two of the carbons may be linked via a suitable element orgroup. Thus, the hydrocarbyl group may contain heteroatoms. Suitableheteroatoms will be apparent to those skilled in the art and include,for instance, sulphur, nitrogen, oxygen, silicon and phosphorus. Ofthese heteroatoms oxygen is particularly preferred. Therefore, in oneaspect the hydrocarbyl group may for example be an alkoxy group.

Each hydrocarbyl group including the unsaturated cyclic hydrocarbylgroup of A and the unsaturated cyclic hydrocarbyl group of B mayoptionally be substituted with one or more substituent. Any suchsubstituent is preferably inert under the reaction conditions employedin the preparation of the compounds of formula (I) and preferably shouldnot give unfavourable interactions with a liquid hydrocarbon fuel orother additives employed in such a fuel. Substituents meeting theseconditions will be readily apparent to a person skilled in the art.

Examples of suitable substituents are alkyl, substituted alkyl, alkoxy,substituted alkoxy, aryl, substituted aryl, arylalkyl, substitutedarylalkyl groups and cyclic groups such as cycloalkyl. In addition tothe possibility of the substituents being a cyclic group, a combinationof substituents may form a cyclic group. Suitable substituents for thesubstituted groups include alkyl, halo, hydroxy, nitro, alkoxy, aryl,cyclic, ester groups and combinations thereof. In the case ofsubstituted arylalkyl groups, the substituent or substituents may bepresent on the aryl and/or the alkyl portion of the group. The term“alkyl” or the alkyl portion of an alkoxy or arylalkyl group, may bestraight chain or branched chain.

A typical hydrocarbyl group is a hydrocarbon group. Here the term“hydrocarbon” means any one of an alkyl group, an alkenyl group, analkynyl group, which groups may be linear, branched or cyclic, or anaryl group. The term hydrocarbon also includes those groups but whereinthey have been optionally substituted. If the hydrocarbon is a branchedstructure having substituent(s) thereon, then the substitution may be oneither the hydrocarbon backbone or on the branch; alternatively thesubstitutions may be on the hydrocarbon backbone and on the branch.

A typical hydrocarbon group is an alkyl group.

The hydrocarbyl/hydrocarbon/alkyl may be straight chain or branchedand/or may be saturated or unsaturated.

By the term “R₁—C—R₂ backbone” it is meant the longest chain of directlybonded atoms within the R₁—C—R₂ moiety. It will be understood that achain does not include atoms of cyclic substituents or substituents of aterminal carbon.

Unless otherwise stated the weight percent (wt %) of iron is measured at−30° C. and 1 atmosphere pressure.

By the term “plastics material incompatible with aromatic diluent orcarrier” it is meant a plastics material which undergoes distortionand/or which exhibits mean solvent loss of an aromatic diluent orcarrier by permeation of greater than 2% per year, such as greater than5%, or such as greater than 10% per year.

The term “aromatic” as used herein relates to a diluent or carrier witha total aromatic substance content of greater than 98% by weight.Typical aromatic substances are aromatic compounds having 9 to 16 carbonatoms and a boiling range of 170° C. to 295° C. PLUTOsol™ APF is anexample of an aromatic diluent or carrier.

The term “non-aromatic or low-aromatic” as used herein relates to adiluent or carrier with a total aromatic substance content of less than30 wt %. Preferably, the term “non-aromatic or low-aromatic” as usedherein relates to a diluent or carrier with a total aromatic substancecontent of less than 20 wt %, preferably less than 10 wt %, preferablyless than 5 wt %, preferably less than 1 wt % such as less than 0.5 wt%, preferably less than 0.1 wt % such as less than 0.05 wt %. Isopar Lis an example of a non-aromatic or low-aromatic diluent or carrier andhas a total aromatic substance content of less than 0.05 wt %.

The term “carbon-based particulates”, as used herein, includescarbon-based particulates which are typically formed by incompletecombustion of the fuel within the combustion system but which may alsobe formed from combustion of lubricating oil or other organic-basedmaterials used within the combustion system. Typical carbon-basedparticles include soot particles.

The term “regeneration temperature” as used herein relates to theminimum exhaust gas temperature at which trapped carbon-basedparticulates may be oxidised to gaseous products. The regenerationtemperature may also be defined as the exhaust gas temperature at whichthe rate of deposit of carbon-based particulates on the diesel particlefilter is equal to the rate of removal of carbon-based particulates fromthe diesel particle filter by oxidation to gaseous products. This isknown as the balance point of the DPF. Further details on balance pointsand methods of determining them may be found in U.S. Pat. No. 6,003,303or in P L Herzog, 2000, ATA, vol. 53, No. 11/12, pages 389-397.

Composition

As previously mentioned, in one aspect the present invention provides acomposition comprising: i) at least one compound of formula (I):

wherein R₁ and R₂ are independently selected from a group consisting ofhydrogen, unsubstituted or substituted C₁₋₁₉ hydrocarbyl or a group offormula (II):

wherein Q is a bond or an unsubstituted or substituted hydrocarbylgroup; wherein R₃ is selected from a group consisting of hydrogen andunsubstituted or substituted C₁₋₁₈ hydrocarbyl; wherein the R₁—C—R₂backbone is from 5 to 20 atoms in length; wherein each A and B isindependently an unsubstituted or substituted unsaturated cyclichydrocarbyl group; and wherein n is an integer from 0 to 10; and ii) adiluent or carrier; wherein the compound(s) of formula (I) is present inan amount sufficient to provide, at −30° C., at least 1 wt % of iron,based on the weight of the composition.Diluent or Carrier

In one aspect the diluent or carrier is a solvent. In one aspect thediluent or carrier is a low-aromatic or non-aromatic diluent or carrier.In one aspect the diluent or carrier is a low-aromatic or non-aromaticsolvent.

It will be readily understood that the compound(s) of formula (I) may bedissolved in the diluent or carrier to form a solution or may besuspended in the diluent or carrier to form a suspension. In one aspecta proportion of the compound(s) of formula (I) is dissolved in thediluent or carrier and a proportion of the compound(s) of formula (I) issuspended in the diluent or carrier. In a preferred aspect substantiallyall of the compound(s) of formula (I) is dissolved in the diluent orcarrier. By the term “substantially all” is meant more than 90%,preferably more than 95%, preferably more than 98% of the compound(s) offormula (I).

Preferred diluents or carriers are low-aromatic or non-aromatic diluentsor carriers which have an initial boiling point of greater than 100° C.,preferably at least 160° C. and consequently have low vapour pressure,such that evaporative loss does not lead to significant changes in ironconcentration on long-term storage. Preferred non-aromatic orlow-aromatic diluents or carriers are those with a total aromaticsubstance content of less than 10% by weight, preferably less than 1% byweight, preferably less than 0.5% by weight. An example of a preferrednon-aromatic or low-aromatic diluent or carrier is Isopar L.

The use of a non-aromatic or low-aromatic diluent or carrier improvesease of handling and storage in particular with regard to health andsafety considerations and also allows compatibility with supplycontainers formed from a range of plastics materials such as HDPE.

-   R₁—C—R₂

In one aspect when the R₁—C—R₂ backbone is 5, 7 or 19 atoms in length,the backbone is substituted.

In one aspect the R₁—C—R₂ backbone is substituted.

In one aspect the R₁—C—R₂ backbone is from 6 to 20 atoms in length. Inone aspect the R₁—C—R₂ backbone is from 7 to 20 atoms in length. In oneaspect the R₁—C—R₂ backbone is from 8 to 20 atoms in length. In oneaspect, the R₁—C—R₂ backbone is from 14 to 20 atoms in length.

In one aspect the R₁—C—R₂ backbone is from 5 to 18 atoms in length,preferably 6 to 18 atoms in length, preferably 8 to 18 atoms in length,preferably 14 to 18 atoms in length.

In one preferred aspect the R₁—C—R₂ backbone is from 7 to 10 atoms inlength. In one aspect the R₁—C—R₂ backbone is 7 atoms in length. In oneaspect the R₁—C—R₂ backbone is 8 atoms in length. In one aspect theR₁—C—R₂ backbone is 9 atoms in length. In one aspect the R₁—C—R₂backbone is 10 atoms in length.

-   R₁ and R₂

In one aspect R₁ and R₂ are independently selected from H andunsubstituted or substituted C₁₋₁₉ hydrocarbyl group. In one aspect R₁and R₂ are independently selected from H and unsubstituted orsubstituted C₄₋₁₉ hydrocarbyl group. In one aspect R₁ and R₂ areindependently selected from H and unsubstituted or substituted C₄₋₁₀hydrocarbyl group. In one aspect R₁ and R₂ are independently selectedfrom H and unsubstituted or substituted C₇₋₁₉ hydrocarbyl group. In oneaspect R₁ and R₂ are independently selected from H and unsubstituted orsubstituted C₇₋₁₀ hydrocarbyl group.

In one aspect R₁ and R₂ are independently selected from H andunsubstituted or substituted C₁₋₁₉ hydrocarbon group. In one aspect R₁and R₂ are independently selected from H and unsubstituted orsubstituted C₄₋₁₉ hydrocarbon group. In one aspect R₁ and R₂ areindependently selected from H and unsubstituted or substituted C₄₋₁₀hydrocarbon group. In one aspect R₁ and R₂ are independently selectedfrom H and unsubstituted or substituted C₇₋₁₉ hydrocarbon group. In oneaspect R₁ and R₂ are independently selected from H and unsubstituted orsubstituted C₇₋₁₀ hydrocarbon group.

The term “hydrocarbon” means any one of an alkyl group, an alkenylgroup, an alkynyl group, which groups may be linear, branched or cyclic,or an aryl group. The term hydrocarbon also includes those groups butwherein they have been optionally substituted. If the hydrocarbon is abranched structure having substituent(s) thereon, then the substitutionmay be on either the hydrocarbon backbone or on the branch;alternatively the substitutions may be on the hydrocarbon backbone andon the branch.

In one aspect R₁ and R₂ are independently selected from H andunsubstituted or substituted C₁₋₁₉ alkyl group. In one aspect R₁ and R₂are independently selected from H and unsubstituted or substituted C₄₋₁₉alkyl group. In one aspect R₁ and R₂ are independently selected from Hand unsubstituted or substituted C₄₋₁₀ alkyl group. In one aspect R₁ andR₂ are independently selected from H and unsubstituted or substitutedC₇₋₁₉ alkyl group. In one aspect R₁ and R₂ are independently selectedfrom H and unsubstituted or substituted C₇₋₁₀ alkyl group.

In one aspect at least one R₁ group is independently selected fromhydrogen, methyl and ethyl. In a preferred aspect each R₁ group isindependently selected from hydrogen, methyl and ethyl.

In one aspect at least one R₁ group is hydrogen. In a preferred aspecteach R₁ group is hydrogen.

In one aspect at least one R₁ group is methyl. In a preferred aspecteach R₁ group is methyl.

In one aspect at least one R₁ group is ethyl. In a preferred aspect eachR₁ group is ethyl.

In one aspect at least one R₂ group is a group selected from anunsubstituted or substituted C₂₋₁₉ hydrocarbyl group, an unsubstitutedor substituted C₃₋ ₁₉ hydrocarbyl group, an unsubstituted or substitutedC₄₋₁₉ hydrocarbyl group, an unsubstituted or substituted C₅₋₁₉hydrocarbyl group, an unsubstituted or substituted C₆₋₁₉ hydrocarbylgroup, an unsubstituted or substituted C₇₋₁₉ hydrocarbyl group, anunsubstituted or substituted C₆₋₁₅ hydrocarbyl group, an unsubstitutedor substituted C₇₋₁₅ hydrocarbyl group, an unsubstituted or substitutedC₄₋₁₀ hydrocarbyl group, an unsubstituted or substituted C₆₋₁₀hydrocarbyl group, and an unsubstituted or substituted C₇₋₁₀ hydrocarbylgroup.

In one aspect at least one R₂ group is a group selected from anunsubstituted or substituted C₂₋₁₉ hydrocarbon group, an unsubstitutedor substituted C₃₋₁₉ hydrocarbon group, an unsubstituted or substitutedC₄₋₁₉ hydrocarbon group, an unsubstituted or substituted C₅₋₁₉hydrocarbon group, an unsubstituted or substituted C₆₋₁₉ hydrocarbongroup, an unsubstituted or substituted C₇₋₁₉ hydrocarbon group, anunsubstituted or substituted C₆₋₁₅ hydrocarbon group, an unsubstitutedor substituted C₇₋₁₅ hydrocarbon group, an unsubstituted or substitutedC₄₋₁₀ hydrocarbon group, an unsubstituted or substituted C₆₋₁₀hydrocarbon group, and an unsubstituted or substituted C₇₋₁₀ hydrocarbongroup.

In one aspect at least one R₂ group is a group selected from anunsubstituted or substituted C₂₋₁₉ alkyl group, an unsubstituted orsubstituted C₃₋₁₉ alkyl group, an unsubstituted or substituted C₄₋₁₉alkyl group, an unsubstituted or substituted C₅₋₁₉ alkyl group, anunsubstituted or substituted C₆₋₁₉ alkyl group, an unsubstituted orsubstituted C₇₋₁₉ alkyl group, an unsubstituted or substituted C₆₋₁₅alkyl group, an unsubstituted or substituted C₇₋₁₅ alkyl group, anunsubstituted or substituted C₄₋₁₀ alkyl group, an unsubstituted orsubstituted C₆₋₁₀ alkyl group, and an unsubstituted or substituted C₇₋₁₀alkyl group.

In one aspect each R₂ group is a group selected from an unsubstituted orsubstituted C₂₋₁₉ hydrocarbyl group, an unsubstituted or substitutedC₃₋₁₉ hydrocarbyl group, an unsubstituted or substituted C₄₋₁₉hydrocarbyl group, an unsubstituted or substituted C₅₋₁₉ hydrocarbylgroup, an unsubstituted or substituted C₆₋₁₉ hydrocarbyl group, anunsubstituted or substituted C₇₋₁₉ hydrocarbyl group, an unsubstitutedor substituted C₆₋₁₅ hydrocarbyl group, an unsubstituted or substitutedC₇₋₁₅ hydrocarbyl group, an unsubstituted or substituted C₄₋₁₀hydrocarbyl group, an unsubstituted or substituted C₆₋₁₀ hydrocarbylgroup, and an unsubstituted or substituted C₇₋₁₀ hydrocarbyl group.

In one aspect each R₂ group is a group selected from an unsubstituted orsubstituted C₂₋₁₉ hydrocarbon group, an unsubstituted or substitutedC₃₋₁₉ hydrocarbon group, an unsubstituted or substituted C₄₋₁₉hydrocarbon group, an unsubstituted or substituted C₅₋₁₉ hydrocarbongroup, an unsubstituted or substituted C₆₋₁₉ hydrocarbon group, anunsubstituted or substituted C₇₋₁₉ hydrocarbon group, an unsubstitutedor substituted C₆₋₁₅ hydrocarbon group, an unsubstituted or substitutedC₇₋₁₅ hydrocarbon group, an unsubstituted or substituted C₄₋₁₀hydrocarbon group, an unsubstituted or substituted C₆₋₁₀ hydrocarbongroup, and an unsubstituted or substituted C₇₋₁₀ hydrocarbon group.

In one aspect each R₂ group is a group selected from an unsubstituted orsubstituted C₂₋₁₉ alkyl group, an unsubstituted or substituted C₃₋₁₉alkyl group, an unsubstituted or substituted C₄₋₁₉ alkyl group, anunsubstituted or substituted C₅₋₁₉ alkyl group, an unsubstituted orsubstituted C₆₋₁₉ alkyl group, an unsubstituted or substituted C₇₋₁₉alkyl group, an unsubstituted or substituted C₆₋₁₅ alkyl group, anunsubstituted or substituted C₇₋₁₅ alkyl group, an unsubstituted orsubstituted C₄₋₁₀ alkyl group, an unsubstituted or substituted C₆₋₁₀alkyl group, and an unsubstituted or substituted C₇₋₁₀ alkyl group.

In one aspect at least one R₂ group is unsubstituted. In a preferredaspect each R₂ group is unsubstituted.

Preferably the atom of R₂ bonded to the carbon of formula (I) is notsubstituted with an alkyl group. Preferably the atom of R₂ bonded to thecarbon of formula (I) is unsubstituted.

In one aspect at least one R₂ group is substituted with one or moresubstituents selected from alkyl, aryl, arylalkyl and alkaryl groups. Inone aspect each R₂ group is substituted with one or more substituentsselected from alkyl, aryl, arylalkyl and alkaryl groups.

In one aspect at least one R₂ group is substituted with one or morealkyl groups. In one aspect each R₂ group is substituted with one ormore alkyl groups.

In one aspect, alternate carbons in the backbone of at least one R₂group, preferably each R₂ group, are substituted, preferablydisubstituted. In this aspect, the substituents are preferably alkyl,more preferably methyl. In this aspect the substituents are preferablythe same. An example of a preferred R₂ group in this aspect is apolyisobutene (PIB). A polyisobutene group typically has the followingformula:

wherein q is an integer, preferably an integer from 1 to 10, morepreferably from 3 to 8, such as 3, 4 or 5.

In one aspect at least one R₂ group is a group of formula (VI),preferably each R₂ group is a group of formula (VI):

In one aspect at least one R₂ group, preferably each R₂ group, is agroup of formula (II):

wherein Q is a bond or an unsubstituted or substituted hydrocarbylgroup; and wherein

R₃ is selected from a group consisting of hydrogen and unsubstituted orsubstituted C₁₋₁₈ hydrocarbyl.

In one aspect at least one R₂ group, preferably each R₂ group, is agroup of formula (VII):

wherein x is a positive integer; and wherein R₃ is selected from a groupconsisting of hydrogen and unsubstituted or substituted C₁₋₁₈hydrocarbyl.

In one aspect at least one R₂ group, preferably each R₂ group, is agroup of formula (III):

wherein m is a positive integer; and wherein R₃ is selected from a groupconsisting of hydrogen and unsubstituted or substituted C₁₋₁₈hydrocarbyl.

Preferably m is an integer of at least 2. In one preferred aspect m is2. In another preferred aspect m is 3. In a further preferred aspect, mis 4.

Preferably R₃ is selected from a group consisting of hydrogen, methyland ethyl. In a preferred aspect R₃ is selected from a group consistingof hydrogen and methyl.

-   A and B

As discussed above the term “hydrocarbyl” as used herein relates to agroup comprising at least C and H. If the hydrocarbyl group comprisesmore than one C then those carbons need not necessarily be linked toeach other. For example, at least two of the carbons may be linked via asuitable element or group. Thus, the hydrocarbyl group may containheteroatoms. Suitable heteroatoms will be apparent to those skilled inthe art and include, for instance, sulphur, nitrogen, oxygen, siliconand phosphorus. If a heteroatom is present, it is preferably oxygen.

The unsaturated cyclic hydrocarbyl group of A and/or the unsaturatedcyclic hydrocarbyl group of B may, for example be a heterocyclic group.

In one aspect each A and B contains from 3 to 10 atoms in the ring,preferably 4, 5 or 6 atoms in the ring, more preferably 5 atoms in thering.

In one aspect each A and B is independently an unsubstituted orsubstituted aromatic hydrocarbyl ring. Preferably, each A and B isindependently an unsubstituted or substituted aromatic carbon ring.

In one aspect, one or more of A and/or one or more of B is substitutedwith one or more substituents selected from alkoxy, alkyl, aryl,arylalkyl and alkaryl groups each of which substituents may be eitherunsubstituted or substituted. It has been found that compounds of thistype typically show increased solubility compared with compounds whereinA and B are unsubstituted.

If one or more of A and/or one or more of B is substituted then they mayadvantageously be substituted with one or more substituents selectedfrom alkyl, aryl, arylalkyl and alkaryl groups, preferably selected fromalkyl and aryl groups, each of which substituents may be substituted orunsubstituted. If one or more of A and/or one or more of B issubstituted then they are preferably substituted with one or more alkylgroups, preferably one or more C₁₋₄alkyl groups.

It has been found that when one or more of A and/or one or more of B issubstituted, the R₁—C—R₂ backbone may be from 1 to 20 atoms in length,such as from 1 to 10 atoms in length, preferably from 1 to 5 atoms inlength, such as 3 atoms in length. Thus, in one aspect the presentinvention provides a composition comprising: i) at least one compound offormula (I):

wherein R₁ and R₂ are independently selected from a group consisting ofhydrogen, unsubstituted or substituted C₁₋₁₉ hydrocarbyl or a group offormula (II):

wherein Q is a bond or an unsubstituted or substituted hydrocarbylgroup; wherein R₃ is selected from a group consisting of hydrogen andunsubstituted or substituted C₁₋₁₈ hydrocarbyl; wherein the R₁—C—R₂backbone is from 1 to 20 atoms in length; wherein each A and B isindependently an unsubstituted or substituted unsaturated cyclichydrocarbyl group; wherein at least one of A and B is a substitutedunsaturated cyclic hydrocarbyl group; and wherein n is an integer from 0to 10; and ii) a diluent or carrier; wherein the compound(s) of formula(I) is present in an amount sufficient to provide, at −30° C., at least1 wt % of iron, based on the weight of the composition.

In a preferred aspect each A and B is unsubstituted. Compounds of thistype may be preferred because they may typically be less expensive thancompounds wherein one or more of A and/or one or more of B issubstituted.

In one aspect each A and B is the same.

In one aspect, one or more of A and/or one or more of B iscyclopentadienyl. Preferably in this aspect each A and B iscyclopentadienyl. Preferably in this aspect, each A and B isunsubstituted cyclopentadienyl.

In a preferred aspect the A and B associated with a particular Fe atomwill donate electrons to said Fe atom such that the 18 electron rule isobeyed.

-   n

In one aspect n of formula (I) is 0, 1 or 2. Preferably n is 0.

Preferred Compositions

In one aspect, the present invention provides a composition as hereindefined wherein the at least one compound of formula (I) is selectedfrom compounds of formula (IV):

wherein p is an integer from 4 to 18.

In one aspect p is an integer from 5 to 10, preferably p is 5. Inanother aspect p is an integer from 6 to 10, preferably p is 6 or 7.

Preferably, the compositions according to the present invention arefree, or substantially free, of compound(s) of formula (VIII):

wherein A and B are as herein defined.

In one aspect the compound(s) of formula (I) is other than

wherein Fc denotes ferrocene.

In a highly preferred embodiment the present invention provides acomposition comprising: i) at least one compound of formula (IV):

wherein p is an integer from 6 to 10; and ii) a non-aromatic orlow-aromatic diluent or carrier; wherein the compound(s) of formula (I)is present in an amount sufficient to provide, at −30° C., at least 4 wt% of iron, based on the weight of the composition.

The composition according to the present invention may comprise one ormore additives for example, to improve various aspects of the fuel towhich the composition is typically added or to improve various aspectsof the combustion system performance. Suitable additional additivesinclude detergents, carrier oils, anti-oxidants, corrosion inhibitors,colour stabilisers, metal deactivators, cetane number improvers, othercombustion improvers, antifoams, pour point depressants, cold filterplugging depressants, wax anti-settling additives, dispersants,reodorants, dyes, smoke suppressants, lubricity agents, and otherparticulate filter regeneration additives.

Method for the Preparation of Compounds of Formula I

The compounds of the present invention may be made in accordance withnovel or known processes. A typical general synthetic route which may befollowed to prepare the compounds of the present invention is disclosedin U.S. Pat. No. 3,673,232.

Compounds of formula (I), such as those wherein n is zero and each A andB is an unsubstituted cyclopentadienyl ring, may, for example, beprepared by the condensation of two equivalents of ferrocene with oneequivalent of a carbonyl compound such as a ketone or aldehyde or anequivalent such as a ketal or acetal, respectively. In U.S. Pat. No.3,673,232 this is accomplished by addition of the carbonyl compound orequivalent to a two phase system composed of a solution of strong acid,e.g. sulphuric acid, in alcohol, e.g. methanol, and a solution offerrocene in an organic solvent, such as toluene, or a suspension offerrocene in ferrocene-saturated solvent, such as toluene. Compounds offormula (I), such as those wherein n is zero and one or more of A and/orB is a substituted cyclopentadienyl ring, may be prepared in ananalogous manner by the condensation of two equivalents of substitutedferrocene, such as an alkyl ferrocene, with one equivalent of a carbonylcompound such as a ketone or aldehyde or an equivalent such as a ketalor acetal, respectively. Where the ferrocene or substituted ferrocene,used as starting material, is a liquid (e.g. molten) at the reactiontemperature used in the preparation, then the two-phase system maycomprise such liquid (e.g. molten) ferrocene compound in the absence ofthe organic solvent.

A mixture of starting materials may be used and a mixture of differentcompounds of formula (I) may thus be obtained. For example, a mixture ofdifferent aldehydes and/or a mixture of different ketones may be used asstarting materials. Additionally or alternatively, a mixture ofdifferently substituted ferrocenes or a mixture of ferrocene and one ormore substituted ferrocene may be used as starting materials.

Compounds of formula (I) such as those wherein n is greater than zero,may be prepared by adjusting the molar quantity of carbonyl compound orequivalent relative to the molar quantity of ferrocene or substitutedferrocene, and/or by adjusting the addition profile of the carbonylcompound or equivalent and/or by extending reaction times. For example,reaction of 0.67 equivalents of octanal per molar equivalent offerrocene will produce a product containing a mixture of unreactedferrocene, a compound of formula (I) in which n is 0, a compound offormula (I) in which n is 1, and possibly one or more compounds offormula (I) wherein n is 2 or greater than 2. Addition of the octanal intwo stages, first 0.6 equivalents then a further 0.3 equivalents whenthe reaction is substantially complete, would give a mixture containinga somewhat higher proportion of a compound of formula (I) in which n is2, than the procedure described above involving the reaction of 0.67equivalents of octanal. The relative proportions of oligomeric speciespresent can also be adjusted by changing the addition profile of boththe ferrocene and the carbonyl compound or equivalent. Thus a highproportion of compound of formula (I) in which n is 1 should result fromtreatment of the reaction product of two molar equivalents of ferrocenewith one of octanal, followed by addition of a further equivalent ofeach of ferrocene and octanal.

Compounds of formula (I) wherein R₁ or R₂ is a group of formula (II),may be prepared by using, as the carbonyl compound or equivalent in theprocess outlined above, a suitable di-carbonyl species or equivalent,such as a dialdehyde or a diketone. Appropriate care needs to be takenwith regard to the number of molar equivalents of each material present.

It has surprisingly been found that the compounds of formula (I) may beliquid at the temperature of interest and may therefore be used in thesubstantial absence of solvent.

In one aspect the present invention provides a compound of formula (I):

wherein R₁ and R₂ are independently selected from a group consisting ofhydrogen, unsubstituted or substituted C₁₋₁₉ hydrocarbyl or a group offormula (II):

wherein Q is a bond or an unsubstituted or substituted hydrocarbylgroup; wherein R₃ is selected from a group consisting of hydrogen andunsubstituted or substituted C₁₋₁₈ hydrocarbyl; wherein the R₁—C—R₂backbone is from 5 to 20 atoms in length; wherein each A and B isindependently an unsubstituted or substituted unsaturated cyclichydrocarbyl group; and wherein n is an integer from 0 to 10.

In a further aspect the present invention provides a compound of formula(I):

wherein R₁ and R₂ are independently selected from a group consisting ofhydrogen, unsubstituted or substituted C₁₋₁₉ hydrocarbyl or a group offormula (II):

wherein Q is a bond or an unsubstituted or substituted hydrocarbylgroup; wherein R₃ is selected from a group consisting of hydrogen andunsubstituted or substituted C₁₋₁₈ hydrocarbyl; wherein the R₁—C—R₂backbone is from 1 to 20 atoms in length; wherein each A and B isindependently an unsubstituted or substituted unsaturated cyclichydrocarbyl group; wherein at least one of A and B is a substitutedunsaturated cyclic hydrocarbyl group; and wherein n is an integer from 0to 10; and ii) a diluent or carrier; wherein the compound(s) of formula(I) is present in an amount sufficient to provide, at −30° C., at least1 wt % of iron, based on the weight of the composition.Iron Content

As previously mentioned, unless otherwise stated the weight percent (wt%) of iron is measured at −30° C. and 1 atmosphere pressure.

In one aspect, the present invention provides a composition as hereindefined wherein the compound(s) of formula (I) is present in an amountsufficient to provide at least 2.5 wt % of iron, preferably at least 4.0wt % of iron, more preferably at least 5.0 wt % of iron, based on theweight of the composition.

In a preferred aspect, at −40° C. the compound(s) of formula (I) ispresent in an amount sufficient to provide at least 1 wt % or iron,preferably at least 2.5 wt % of iron, preferably at least 4.0 wt % ofiron, more preferably at least 5.0 wt % of iron, based on the weight ofthe composition.

Preferably, the composition has an iron content of up to 10 wt %. Aconcentration of iron up to a maximum of 25.5 wt % is advantageouslypresent in the composition according to the present invention.

It will be readily appreciated that a compound of formula (I) mayexhibit even greater solubility and/or dispersibility in an aromaticdiluent or carrier than in a non-aromatic or low-aromatic diluent orcarrier. Thus, in one aspect, the present invention provides acomposition comprising a compound of formula (I) as herein defined andan aromatic diluent or carrier. In this aspect, preferably thecompound(s) of formula (I) is present at room temperature and pressurein an amount sufficient to provide at least 5 wt % of iron, based on theweight of the composition. More preferably the compound(s) of formula(I) is present at 0° C. in an amount sufficient to provide at least 5 wt% of iron, based on the weight of the composition. More preferably thecompound(s) of formula (I) is present at −25° C. in an amount sufficientto provide at least 5 wt % of iron, based on the weight of thecomposition. In a highly preferred aspect the compound(s) of formula (I)is present at −40° C. in an amount sufficient to provide at least 5 wt %of iron, based on the weight of the composition. A suitable aromaticdiluent or carrier is PLUTOsol™ APF.

Fuel Additive Dosing Apparatus

As previously mentioned, in one aspect the present invention provides afuel additive dosing apparatus comprising a supply container formed froma plastics material incompatible with an aromatic diluent or carrier anda composition contained within the supply container comprising: i) atleast one compound of formula (I):

wherein R₁ and R₂ are independently selected from a group consisting ofhydrogen, unsubstituted or substituted C₁₋₁₉ hydrocarbyl or a group offormula (II):

wherein Q is a bond or an unsubstituted or substituted hydrocarbylgroup; wherein R₃ is selected from a group consisting of hydrogen andunsubstituted or substituted C₁₋₁₈ hydrocarbyl; wherein the R₁—C—R₂backbone is from 5 to 20 atoms in length; wherein each A and B isindependently an unsubstituted or substituted unsaturated cyclichydrocarbyl group; and wherein n is an integer from 0 to 10; and ii) alow aromatic or non-aromatic diluent or carrier.

In this aspect, preferably the supply container is formed from HDPE. Theterm “HDPE” is an abbreviation for high density polyethylene.

In this aspect preferably the composition is a composition as hereindefined.

Fuel

As previously mentioned, in one aspect the present invention provides afuel composition comprising: (a) a fuel; and (b) a compound of formula(I):

wherein R₁ and R₂ are independently selected from a group consisting ofhydrogen, unsubstituted or substituted C₁₋₁₉ hydrocarbyl or a group offormula (II):

wherein Q is a bond or an unsubstituted or substituted hydrocarbylgroup; wherein R₃ is selected from a group consisting of hydrogen andunsubstituted or substituted C₁₋₁₈ hydrocarbyl; wherein the R₁—C—R₂backbone is from 5 to 20 atoms in length; wherein each A and B isindependently an unsubstituted or substituted unsaturated cyclichydrocarbyl group; and wherein n is an integer from 0 to 10.

In one aspect the fuel is a fuel for spark ignition engines such asgasoline.

Preferably the fuel is a fuel for a high compression spontaneousignition engine.

Preferably the fuel is diesel. The diesel may be biodiesel, low sulphurdiesel and ultra-low sulphur diesel.

Method

As previously mentioned, in one aspect the present invention provides amethod of regenerating a particulate filter located in an exhaust systemof a combustion system for fuel, which comprises contacting carbon-basedparticulates, present in the particulate filter, with combustionproducts of a composition as herein defined.

Preferably the composition is located in a container associated with thecombustion system for introduction into fuel prior to combustion of thefuel in the combustion system.

Use

As previously mentioned, in one aspect the present invention providesuse of a composition as herein defined for decreasing the regenerationtemperature of a particulate filter located in the exhaust system of acombustion system.

When a composition according to the present invention is supplied to afuel and the fuel is supplied to a combustion system, the compositionreacts in the combustion system to produce combustion productscontaining iron-containing species such as iron oxide(s). Combustion ofthe fuel, and possibly lubricating oil or other organic carbon-basedmaterials, within the combustion system produces combustion productswhich typically contain carbon-based particulates. The combustionproducts arising from the combustion of the composition according to thepresent invention which comprise solid iron-containing species such asiron oxide(s), and the carbon-based particulates, are intimately mixedin the exhaust gases from the combustion system and the particulatematerial is filtered out by the particulate filter. Whilst not wishingto be bound by theory, it is believed that particulate material presentin the combustion products of a composition according to the presentinvention, which particulate material comprises iron-containing speciessuch as iron oxide(s), is responsible for, or at least contributes to, alowering of the ignition temperature of the carbon-based particulatesand, hence, the regeneration temperature of the particulate filter.Therefore, at the operating temperature of the filter, episodes ofspontaneous ignition occur and the carbon-based particulates, e.g. sootparticles, are burned off to produce gaseous products.

Alternatively, means may be used to raise the temperature of theparticulate filter or of the exhaust gases, thereby obtaining aso-called “forced regeneration” with the presence of the productsobtained from the combustion of a composition according to the presentinvention, serving to reduce the input of energy required to achieve the“forced regeneration”. Consequently, in combustion systems comprisingparticulate filters which are present in the exhaust side of the systemand designed for permanent operation, and which thus need to beregenerated, the use of a composition according to the present inventionmay avoid the need for costly additional measures or installations, e.g.burners, electric heaters or additional catalytic systems, for burningoff the carbon-based particles which have been filtered out. This meansthat particulate filters, e.g. diesel particulate filters, can beinstalled cost-effectively for permanent use without large additionalexpenditure. In one alternative embodiment, one or more of theabove-mentioned additional measures may be employed in which case theireffectiveness and/or cost effectiveness, particularly where extra fuelis burned to raise the exhaust gas temperature, may be enhanced by theuse of a composition according to the present invention, or lower treatrates of a composition according to the present invention may be used.

The composition according to the present invention may be used invarious types of combustion systems wherein particulate emissions areregarded as a problem, for example, spark ignition engines usinggasoline, and especially gasoline direct injection engines. Preferablythe composition according to the present invention is used in highcompression spontaneous ignition engines, such as diesel engines.

Fuels that may be used in high compression spontaneous ignition enginesare typically conventional fuels for such engines, particularly dieselfuel, including biodiesel, low sulphur diesel and ultra-low sulphurdiesel.

Preferably, the composition according to the present invention ismetered into the fuel, for example from a supply container. This meteredaddition to the fuel may, for example, take place shortly before thefuel is supplied to the combustion system which may be an internalcombustion engine present in a vehicle. Alternatively, the meteredaddition to the fuel may, for example, take place as or shortly afterthe fuel is charged to the fuel tank supplying the combustion system,e.g. the fuel tank of a vehicle when the combustion system is aninternal combustion engine located in the vehicle.

The composition according to the present invention is typically suppliedto the fuel by means of a metering unit, e.g. by means of a meteringpump, in quantities such that the iron content of the fuel is 0.1-100ppm following the addition. On the one hand, the quantity of thecomposition to be added to the fuel should be great enough to ensureoptimum possible burning off of the carbon-based particulates from theparticulate filter but, on the other hand, should not be excessivelyhigh from the point of view of cost and the eventual partial or completeblockage of the particulate filter that may occur due to ash derivedfrom the addition to the fuel of an excessive amount of the composition.An iron content of the fuel within the range of 1-25 ppm has provenadvantageous, the optimum range being 5-15 ppm, in particular in thepreferred combustion system (i.e. high compression spontaneous ignitionengines).

In a preferred aspect the carbon-based particulates, present in theparticulate filter, and the combustion products of the compositionaccording to the present invention, especially solid, typicallyparticulate, material present in the combustion products of thecomposition according to the present invention are intimately mixed. Itis believed that the intimate mixing of the carbon-based particulatesand the particulate material present in the combustion products of thecomposition according to the present invention results in:

-   (a) at least a portion of the surface of the carbon-based    particulates being coated with solid combustion products of the    composition according to the present invention;-   (b) at least a portion of the surface of solid combustion products    of the composition according to the present invention being coated    with the carbon-based particulates; and/or-   (c) solid combustion products of the composition according to the    present invention being intimately mixed with particles of the    carbon-based particulates.

In a preferred aspect the carbon-based particulates and the combustionproducts of the composition according to the present invention, presentin the particulate filter are exposed to both heat and an oxidant gas(e.g. O₂ or NO₂), preferably both the heat and oxidant gas are suppliedwithin the exhaust gases from the combustion system.

Aspects of the invention are defined in the appended claims.

The present invention will now be described in further detail in thefollowing examples.

EXAMPLES Example 1 Solubility in Aromatic Solvent

The existence of any effects on solubility and solution viscosity due tochanges in the substitution on the aromatic ring and/or on the bridginggroup was examined by preparation of a series of bridged ferrocenes i.e.compounds according to formula (I) of the present invention. Two sets ofstandard conditions were employed for the preparation and isolation ofthese products, for use with un-substituted and alkylated ferrocene,respectively. Variation of these conditions to arrive at optimumsyntheses of particular derivatives, in particular to maximise the yieldon ferrocene, minimise formation of side-products such as alkenylatedferrocenes and minimise the effort required to separate the desiredsoluble products, is deemed to be within the scope of those skilled inthe art.

Preparation of Bridged Ferrocenes

Sulphuric acid (98 wt % H₂SO₄, 196 g, 2.0 mol) was added carefully tomethanol (214.4 g, 6.7 mol) in a conical flask. The solution temperaturewas maintained at below 40° C. by cooling (ice-water bath) and changingthe addition rate. The solution was transferred to a jacketed,well-baffled one liter reactor equipped with an overhead turbineagitator, reflux condenser, dropping funnel, thermometer and bottomoutlet. The reactor was then further charged with powdered ferrocene(130.2 g, 0.7 mol) washed in with toluene (130 g).

The reactor contents were then warmed to 80+2° C. by the circulation ofhot oil through the jacket, and were rapidly stirred to create anemulsion of the methanolic phase and toluene slurry. The carbonylcompound (0.35 mol, 1 equivalent) was then charged to the droppingfunnel and added dropwise to the reactor over about 15 minutes at asubstantially uniform rate. The reactor contents were then held, withstrong agitation, at 80°±2° C. for 6 hours before being allowed to coolto ambient temperature overnight.

Where ferrocene crystallised out on cooling this was removed byfiltration. Further toluene (130 g) was then added to the liquid phases,and after a further 15 minutes stirring, water (10 cm³) was added, whererequired to aid phase separation and agitation stopped. Themethanol/sulphuric acid phase was then separated and the organic phasewashed with aqueous base (2×200 cm³ 10% NaHCO₃ or NaOH) then water(2×200 cm³), dried over anhydrous sodium sulphate and separated byfiltration to remove the drying agent. Crude product mixture,contaminated by varying amounts of unreacted ferrocene was recovered byremoval of the toluene at the rotary evaporator.

Isolation of Bridged Ferrocenes

Solid materials were ground in a pestle and mortar in the presence ofheptane and filtered to recover solids. The process was repeated untilthin layer chromatography (Merck Aluminium oxide 150 F₂₅₄ (Type T)stationary phase, 3 to 4 parts EtOH to 1H₂O as mobile phase) indicatedthe solids to be substantially free of ferrocene. The material was thendissolved in a minimal quantity of hot heptane, hot-filtered, thenrecovered by recrystallisation on cooling.

Crude products were on occasion oils free or substantially free ofsolids. The products were found to phase-separate from heptane onrefrigeration and so were separated from ferrocene, which tended toremain in solution. Again, progress was monitored by tic.

On occasion crude products comprised mixtures of oil and solid. Here, ajudgement was made as to which if the above techniques was more likelyto be appropriate (i.e. a sticky solid would be ground with heptane in apestle and mortar, an oil containing suspended solids would be dissolvedin the minimum of hot heptane, then refrigerated). Where time andquantity of material available permitted, trial separations wereperformed. Again, purification method selection and/or progress wasmonitored by tic.

Final and near-complete removal of ferrocene from solid, oil or mixedphases was achieved by sublimation at <0.6 mBar, 80° C.

Preparation of Bridged, Alkylated Ferrocenes

Alkylated ferrocenes provided reaction products with carbonyl compoundsthat were viscous oils at ambient temperature, becoming highly mobile onwarming. Accordingly, emulsions comprising methanolic sulphuric acid andsolutions of alkylated ferrocenes in toluene were treated with 0.5equivalents of carbonyl compound at 80° C., as above. The organic phaseswere separated, washed with base and dried. Toluene solvent andunreacted alkylated ferrocenes were removed by distillation to leave theproducts as oils. No further isolation was required.

Determination of Product Properties

Iron contents of the samples were estimated on the basis of C/H/Nanalysis (Leco CHNS 932). This assumes that all isolated products werefree, or substantially so, of unreacted carbonyl compounds, oroxygen-containing reaction products thereof. Ferrocene contents of thesamples were determined by GC/MS on a Finnigan MAT GCQ (GC/MS), using aSupelco MDN-5S fused silica capillary column (30 m×0.25 mm i.d. 0.25μfilm thickness) initial temperature 40° C., held for 2.1 minutes beforeramping to 200° C. at 10° C.min⁻¹ before holding for 20 minutes,injector temperature 275° C., He flow 40 cm.s⁻¹ constant velocity,calibrated against pure ferrocene.

Where suitably crystalline materials could be obtained, furthercharacterisation was performed using ¹H and ¹³C nmr (Bruker AC200).Integration of cyclopentadienyl protons [shift range 4-4.5 ppm downfieldof TMS (tetramethylsilane) in C₆D₆] against those of anycarbonyl-derived bridging unit was used, where possible, to providequalitative information on the degree of oligomer formation. All spectrawere run in C₆D₆ solution with shifts reported relative to TMS. Wherepossible, carbon atoms were identified as methyl, methylene or methyne,via the DEPT (Distortionless Enhancement by Polarisation Transfer)experiment.

Solubility testing was undertaken using the estimate of Fe content fromC/H/N analysis. Since the iron content of ferrocene is known to be 30 wt%, that present as condensation products was estimated by difference.This procedure assumes the products below to contain substantially onlyC, H and Fe. Masses of product(s) sufficient to provide the requiredconcentration of iron as condensation products were weighed intoscrew-cap vials and made up to 10.00 g with toluene. The samples werecapped, shaken or swirled until homogenous then sealed using Parafilm™.The vials were then kept in an ethylene glycol/water filled bath held at−30° C. and periodically inspected for the appearance of solids orseparation of liquid phases. After at least one week solids wereseparated by rapid filtration and soluble products isolated by removalof solvent under vacuum.

Following analysis of the solids, maximum and minimum solubilities wereestimated from the mass balance.

Viscosities of 2.5 wt % iron solutions were determined using a BohlinInstruments CVO rheometer using a 4° 40 mm cone and plate at shear ratesof either 2 Pa or 0.5 Pa.

TABLE 1 Theoretical Analyses for Condensation Products of Ferroceneswith Carbonyl Compounds Calculated for n = 0 Calculated for n = 1Compound Carbonyl C H Fe C H Fe No. Compound (% m/m) (% m/m) (% m/m) (%m/m) (% m/m) (% m/m) 1. 2- 69.72 7.12 23.16 70.96 7.52 21.52Ethylhexanal 2. Acetonyl 67.18 5.65 27.17 67.52 5.68 26.80 acetone 3.Heptan-4-one 71.00 7.70 21.30 71.94 7.99 20.07 4. Pentanal 68.20 6.4225.37 69.18 6.69 24.13 5. 2,4- 66.86 5.50 27.64 67.16 5.51 27.33Pentanedione 6. Pentan-3-one 70.17 7.33 22.50 70.96 7.52 21.52

The terms calculated for n=0 and n=1 in the table above refer,respectively, to compounds of formula (I) wherein n is 0 or 1. From the¹H nmr spectra integration of the methyl group protons againstcyclopentadienyl ones suggested that, assuming only species wherein n=0and n=1 to be present, about 9 mol % n=1 had resulted.

Compounds 1, 2, 4 and 5 were prepared using ferrocene. Compounds 3 and 6were made using ethylferrocene such that one of A or B in formula (I) isethylcyclopentadienyl, the other being, in each case, cyclopentadienyl.

TABLE 2 Analytical Details for Isolated Compositions. Found ImpliedFerrocene Iron as Compound Carbonyl C H [Fe] Content product No.Compound (% m/m) (% m/m) (% m/m) (% m/m) (% m/m) 1 2-Ethylhexanal 73.208.15 18.65 <1.0 18.65 2 Acetonyl acetone 76.40 7.04 16.56 3.50 15.51 3Heptan-4-one 68.85 6.90 24.25 <1.0 24.25 4 Pentanal 68.79 6.94 24.27 2.023.67 5 2,4-Pentanedione 67.03 5.88 27.09 <1.0 27.09 6 Pentan-3-one70.50 7.45 22.05 <1.0 22.05

TABLE 3 Outcomes of Solubility Determination for the IsolatedCompositions Solubility in Toluene at −30° C. Compound Carbonyl 2.5 wt %5.0 wt % No. Compound Fe Fe Solubility of Fe as product 1 2-EthylhexanalClear Clear 2 Acetonyl acetone Powder Powder Solid not characterisable 3Heptan-4-one Clear Solids Insufficient solids to characterise 4 PentanalClear Clear 5 2,4-Pentanedione Solids Solids 2.05 to 2.26 wt % by massbalance 6 Pentan-3-one Deposit Deposit Minimal deposition in both cases

For comparison, the solubility of iron as ferrocene in toluene wasaround 1 wt %. Dilutions of samples of 5 wt % Fe as the product ofcompound 1 established the solubility limit in toluene of this preferredmaterial to be slightly less than 3.2 wt % at −30° C.

TABLE 3a NMR Spectroscopy Details for Derivatives Isolated asCrystalline Materials 5 2,4-Pentanedione 1.308 (s, 6H) 30.77 (CH₃),33.47 (CH₂) and 101.51 (CH₃—C—CH₂) Cyclopentadienyl 3.93 to 4.01 66.27,66.73 and 68.89 (m, 18H)

TABLE 4 GC/MS Data Compound No. Carbonyl source Component/(level)Comments 1 2-Ethylhexanal 2-ethylhexenyl ferrocene (major) Many isomers,parent ion 296, loss of various alkene fragments Bis 2-ethylhexenylferrocene (minor) Isomers, parent ion at 406, typically loss of hepteneobserved 1,1-diferrocenyl 2-ethylhexane (trace) Parent at 482, firstloss heptene 4 Pentanal 1,1-diferrocenylpentane (good purity) Parent at440, first loss C₄H₉

TABLE 5 Viscosity Data of Compositions in Toluene Solution at 2.5 wt %Fe Viscosity at Compound Carbonyl Source Metallocene −30° C. (mPas) 12-Ethylhexanal Ferrocene 5.1 to 6.4 3 Heptan-4-one Ethylferrocene 5.1 4Pentanal Ferrocene 5.4 5 2,4-Pentanedione Ferrocene 4.7 6 Pentan-3-oneEthylferrocene 5.3Interpretation of Data

Compound 1 demonstrates that branched aldehydes may also be used toprepare 1,1-diferrocenyl alkanes. The GC/MS data for compound 1 alsoshow that where an aldehyde, and by inference a ketone, is branched atthe position α to the carbonyl then a propensity to formalkenyl-substituted ferrocene exists. Without wishing to be bound bytheory it is suspected that an intermediate hydroxyalkyl ferrocene formswhich may react with a further molecule of ferrocene to yield adiferrocenylalkyl or may dehydrate to yield the alkene. Experimentalconditions may be changed by routine experimentation to minimiseformation of such products.

Example 2 Solubility in Non-Aromatic or Low-Aromatic Solvent

A one liter three-necked flask fitted with an overhead stirrer driving aturbine impeller, and as and when appropriate, a thermometer, refluxcondenser and dropping funnel was charged with methanol (158.4 g, 4.95mol). Sulphuric acid (98%, 147 g, 1.47 mol) was then added, withstirring and cooling to keep the temperature below 40° C. The solutionwas rapidly stirred (500 rev/min) and ferrocene (139.5 g, 0.75 mol) andtoluene (139.5 g) charged. The entire mixture was then heated to refluxtemperature. At this temperature the aldehyde, ketone or equivalent(0.45 mol) was then added at a steady rate, via the dropping funnel,over about one hour. Once the addition was complete, the reactionmixture was stirred at the lowest temperature of either a rapid refluxor 95° C. during a further five hours before cooling to about 30° C.

After cooling, further toluene (139.5 g) was added and the emulsionstirred for a further ten minutes. The two phases were then separatedusing a separating funnel. The upper, toluene, layer was then removedand neutralised in a reservoir using saturated sodium hydrogen carbonate(150 cm3). After neutralisation the phases were left to stand for aminimum of two hours, preferably overnight, to separate. The aqueousphase was then discarded and the toluene phase filtered prior to removalof toluene and excess aldehyde, ketone or equivalent by distillationunder the vacuum provided by a water jet pump.

TABLE 6 Carbonyl Compounds Used Carbonyl or equivalent Molecular formulaBoiling point ° C. Pentan-2-one C₅H₁₀O 101-103 Pentan-3-one C₅H₁₀O101-103 Hexanal C₆H₁₂O 131 Hexan-3-one C₆H₁₂O 125 Heptanal C₇H₁₄O 153Heptan-2-one C₇H₁₄O 150-152 Octanal C₈H₁₆O 163 Octan-2-one C₈H₁₆O 173Nonanal C₉H₁₈O 93 (31 hPa) Decanal C₁₀H₂₀O 209 ethyl-3-oxobutyrateC₆H₁₀O₃ 180

The solubilities of the products of the above reactions were determinedon a weight percent iron basis. Solids isolated as described above wereassumed to comprise essentially pure samples of the desired material.Solutions at 5 wt % iron in Isopar L were prepared on this basis, sealedinto vials and stored at −30° C. during at least one week. The solutionswere then removed, rapidly filtered, and the iron content of the liquidphase determined by X-ray spectroscopy using ferrocene as a standard.The solubility of iron as ferrocene itself in Isopar L at −30° C. wasdetermined to be 0.22 wt % by this technique.

TABLE 7 Iron content of Isopar L solutions at −30° C. Desired productCarbonyl Compound Iron content (wt %) 2,2-bis-(ferrocenyl)-pentanePentan-2-one 2.62 3,3-bis-(ferrocenyl)-pentane Pentan-3-one 1.711,1-bis-(ferrocenyl)-hexane Hexanal 3.99 1,1-bis-(ferrocenyl)-hexaneHexanal  4.89* 3,3-bis-(ferrocenyl)-hexane Hexan-3-one 1.381,1-bis-(ferrocenyl)-heptane Heptanal 4.05 2,2-bis-(ferrocenyl)-heptaneHeptan-2-one 3.29 1,1-bis-(ferrocenyl)-octane Octanal 4.601,1-bis-(ferrocenyl)-octane Octanal  4.88* 2,2-bis-(ferrocenyl)-octaneOctan-2-one 2.72 1,1-bis-(ferrocenyl)-nonane Nonanal 4.961,1-bis-(ferrocenyl)-decane Decanal 4.41 3,3-bis-(ferrocenyl)-butyl3-oxo-butyl acetate 2.30 acetate Ferrocene Not applicable 0.22 *= samplefirst purified by dissolving in minimum heptane, cooling torecrystallise ferrocene, filtration and removal of solvent under vacuum.Preparation of Condensation Products of Alkylated Ferrocenes

The procedure described in detail above was followed, save that it wasperformed on an 8-fold larger scale and in the absence of toluenesolvent, using ethyl- and butyl-ferrocenes as starting materials. Theterm ‘mass balance’ refers to the percentage ratio of the found weightof product on removal of volatiles at the rotary evaporator to theanticipated yield, assuming complete conversion to the target species.Molecular weight was determined by cryoscopy in benzene and indicates,once the level of unreacted starting material is taken into account, thedegree to which oligomers (n=1 or higher in formula (I)) are present.

TABLE 8 Reactions from Ethylferrocene Carbonyl Temp Mass Unreactedethyl- Theory/found compound (° C.) balance (%) ferrocene (%) MWt(Dalton) Acetone 80 72.2 11.7 468/468 Acetone 98 76.4 14.4 468/523Propanal 81.8 7.5 468/500 Pentanal 90 86.6 0.5 496/494 Pentan-2-one 9541.3 33.2 496/449 Pentan-3-one 80 24.2 15.0 496/418 Heptanal 98 88.6 3.2524/525 Heptan-4-one 97 16.0 19.0 524/532

TABLE 9 Reactions from Butylferrocene Carbonyl Temp Mass Unreactedbutyl- Theory/found compound (° C.) balance (%) ferrocene (%) MWt(Dalton) Acetone 80 60.1 8.8 524/503 Acetone* 91 50.4 8.4 524/472Acetone 90 70.9 11.9 524/502 Propanal 97 65.3 4.3 524/536 Pentanal 9075.6 5.0 552/594 Heptanal 95 73.3 1.9 580/594 *2 hour reaction time only

Example 3 HDPE Container Compatibility Testing

Tests were carried out on an additive container fabricated from HDPEwhich contained an aromatic solvent. Aromatic solvent loss by permeationthrough the walls of the container at a temperature of 60° C. wasrecorded. These results were used to calculate the projected annualpermeation loss which is displayed in Table 10 below.

TABLE 10 Projected Annual Container Type Solvent Permeation LossUncoated HDPE Plutosol F aromatic 43.9% solvent

Further tests were carried out on three different combinations ofcontainer and solvent. Results of loss permeation tests at 40° C. wereused to calculate the projected annual permeation loss. The projectedannual permeation loss for each combination is displayed in Table 11below.

TABLE 11 Projected Annual Container Type Solvent Permeation Loss AUncoated HDPE Isopar L aliphatic  0.61% solvent B Co-extruded HDPE withPlutosol F aromatic  0.12% a polyamide barrier solvent C Barrier coatedHDPE Plutosol F aromatic 0.047% (fluorinated to level 5) solvent

The results in Table 10 show that the permeation loss which occurs foran aromatic solvent in an uncoated HDPE container is extremely high.These results clearly demonstrate that aromatic solvents areincompatible with uncoated HDPE containers.

The results in Table 11 show that permeation loss figures for eachcombination of solvent and container are comparable (all less than 1%).Thus use of an aliphatic solvent in an uncoated HDPE container (A) is aviable alternative to prior art use of an aromatic solvent in a modifiedHDPE container (B or C).

Example 4 Solubility in Non-Aromatic or Low-Aromatic Solvent

Preparation of Compounds

Sulphuric acid (98 wt % H₂SO₄, 196 g, 2.0 mol) was added carefully tomethanol (214.4 g, 6.7 mol) in a round bottom 3 necked flask cooled tobelow 10° C. in an ice/acetone bath.

The solution was transferred to a one liter reactor equipped with anoverhead stirrer, reflux condenser, dropping funnel, and thermometer.The reactor was then further charged with powdered ferrocene (186 g, 1mol) washed in with toluene (186 g).

The reactor contents were then warmed, with vigorous stirring, to 85° C.The aldehyde (0.5 mol) was added dropwise to the reactor over about 1hour and the reactor contents were held, with strong agitation, at 85°C. for 5 hours before being allowed to cool to ambient temperature andleft to stand overnight.

The methanol/sulphuric acid phase was then separated and the organicphase washed with aqueous base (2×200 cm³ 10% NaHCO₃) then water (2×200cm³), dried over anhydrous sodium sulphate and filtered. The crudeproduct was recovered by removal of the toluene at the rotaryevaporator.

The un-reacted ferrocene was removed by vacuum sublimation (24 hrs.70°C.<1 mmHg). Ferrocene contents of the samples were determined by GC/MSon a Finnigan MAT GCQ, using a Supelco MDN-5S fused silica capillarycolumn (30 m×0.25 mm i.d. 0.25μ film thickness). The initial temperature40° C. was held for 2.1 minutes before ramping to 200° C. at 10° C.min⁻¹before holding for 20 minutes. Injector temperature was 275° C. and Heflow 40 cm.s⁻¹ constant velocity. Calibration was against pureferrocene. This procedure also provided a qualitative guide to thepurity of the product and for mass spectra of the components.

TABLE 12 C H Ferrocene Comments on Compound Aldehyde % m/m % m/m % m/mGC/MS data 7. 3,5,5- Ferrocene 71.14 7.82 0.3 Mw pk 496, noTrimethylhexanal higher oligomers. 8. Valeraldehyde Ferrocene 68.96 6.69<0.3 Mw pk 440. Small impurity of higher oligomer mw 508

The result from compound 7 shows that where an aldehyde is branched atthe β-position the alkylene-bridged diferrocene species predominates.

In addition to the samples prepared as set out above, additionalmaterials were prepared by the method of U.S. Pat. No. 3,673,232. Thesecompounds are shown in table 13.

TABLE 13 Com- Substituted Carbonyl pound Ferrocene compound Product 9.Ethylferrocene Pentanal 1,1-bis(ethylferrocenyl)pentane 10.Butylferrocene Pentanal 1,1-bis(butylferrocenyl)pentaneSolubility Testing

The solubility of the isolated samples was determined in Isopar Lsolvent. For the isolated samples of compounds 7 and 8 the C/H/Nanalysis was used to indicate the iron content. For compounds 9 and 10the theoretical iron content was assumed. Solutions were then prepared,at ambient temperatures or with slight warming as required, to a nominaliron content of 5 wt % The samples were then sealed and immersed in abath of ethylene glycol/water cooled and thermostatted to −30° C. during120 hours.

The samples were then individually removed from the bath, taken up intoa 10 cm³ syringe then discharged to a second vial with filtration via aWhatman Anotop 25 0.02 μm in-line filter with Luer hub. Iron contentswere then determined by X-ray fluorescence spectroscopy in an OxfordInstruments ED2000 Ag analyser. The analyser was calibrated againststandards of ferrocene in toluene at iron concentrations of 0.5 through3.0 wt % by 0.5 wt % intervals and against ferrocene in Isopar L at 0.5and 1.0 wt % (approximate ambient temperature solubility limit). Whererequired, dilution of sample materials was employed to bring theconcentration within the range of the calibration.

The results obtained are shown in table 14.

TABLE 14 Wt of Wt of sample sample and Appearance/ease SolubilityCompound (g) solvent (g) of filtration (% m/m Fe) 7 2.42 10.02 Thickslurry of 4.1 tan powder 8 2.12 10.12 Significant quantity 3.1 of tanpowder, but filters well 9 2.29 10.09 Clear, filters well 5.0 10 2.6010.55 Clear, but hard 4.8 to filter

All publications mentioned in the above specification are hereinincorporated by reference. Various modifications and variations of thedescribed methods and system of the invention will be apparent to thoseskilled in the art without departing from the scope and spirit of theinvention. Although the invention has been described in connection withspecific preferred embodiments, it should be understood that theinvention as claimed should not be unduly limited to such specificembodiments. Indeed, various modifications of the described modes forcarrying out the invention which are obvious to those skilled inchemistry or related fields are intended to be within the scope of thefollowing claims

1. A composition located in a container associated with the combustionsystem of a high compression spontaneous ignition engine forintroduction into diesel fuel prior to combustion of the fuel in thecombustion system, the composition comprising: i) at least one compoundof formula (I):

wherein R₁ and R₂ are independently selected from a group consisting ofhydrogen, unsubstituted or substituted C₁₋₁₉ hydrocarbyl or a group offormula (II):

wherein Q is a bond or an unsubstituted or substituted hydrocarbylgroup; wherein R₃ is selected from a group consisting of hydrogen andunsubstituted or substituted C₁₋₁₈ hydrocarbyl; wherein the R₁—C—R₂backbone is from 5 to 20 atoms in length; wherein each A and B isindependently an unsubstituted or substituted unsaturated cyclichydrocarbyl group; and wherein n is an integer from 0 to 10; and ii) adiluent or carrier; wherein the compound(s) of formula (I) is present inan amount sufficient to provide, at −30° C., at least 2.5 wt % of iron,based on the weight of the composition; and wherein substantially all ofthe compound(s) of formula (I) is dissolved in the diluent or carrier.2. A composition according to claim 1 wherein the diluent or carrier isa solvent.
 3. A composition according to claim 1 wherein the diluent orcarrier is a low-aromatic or non-aromatic diluent or carrier.
 4. Acomposition according to claim 1 wherein when the R₁—C—R₂ backbone is 5,7 or 19 atoms in length, the backbone is substituted.
 5. A compositionaccording to claim 1 wherein R₁ and R₂ are independently selected from Hand unsubstituted or substituted C₁₋₁₉ hydrocarbon group.
 6. Acomposition according to claim 1 wherein R₁ and R₂ are independentlyselected from H and unsubstituted or substituted C₁₋₁₉ alkyl group.
 7. Acomposition according to claim 1 wherein at least one or each R₁ groupis independently selected from hydrogen, methyl and ethyl.
 8. Acomposition according to claim 1 wherein at least one or each R₁ groupis hydrogen.
 9. A composition according to claim 1 wherein at least oneor each R₂ group is an unsubstituted or substituted C₄₋₁₉ alkyl group.10. A composition according to claim 1 wherein at least one or each R₂group is an unsubstituted or substituted C₄₋₁₀ alkyl group.
 11. Acomposition according to any one of claim 1 wherein at least one or eachR₂ group is an unsubstituted or substituted C₇₋₁₉ alkyl group.
 12. Acomposition according to claim 11 wherein at least one or each R₂ groupis an unsubstituted or substituted C₇₋₁₅ alkyl group.
 13. A compositionaccording to claim 1 wherein at least one or each R₂ group is anunsubstituted or substituted C₇₋₁₀ alkyl group.
 14. A compositionaccording to claim 1 wherein at least one or each R₂ group isunsubstituted.
 15. A composition according to claim 1 wherein at leastone or each R₂ group is substituted with one or more substituentsselected from alkyl, aryl, arylalkyl and alkaryl groups.
 16. Acomposition according to claim 15 wherein at least one or each R₂ groupis substituted with one or more alkyl groups.
 17. A compositionaccording to claim 1 wherein at least one or each R₂ group is a group offormula (II):

wherein Q is a bond or an unsubstituted or substituted hydrocarbylgroup.
 18. A composition according to claim 17 wherein at least one oreach R₂ group is a group of formula (III):

wherein m is a positive integer.
 19. A composition according to claim 18wherein m is an integer of at least
 2. 20. A composition according toclaim 17 wherein R₃ is selected from a group consisting of hydrogen,methyl and ethyl.
 21. A composition according to claim 1 wherein each Aand B contains from 3 to 10 atoms in the ring.
 22. A compositionaccording to claim 1 wherein each A and B contains 4, 5 or 6 atoms inthe ring.
 23. A composition according to claim 1 wherein, each A and Bgroup contains 5 atoms in the ring.
 24. A composition according to claim1 wherein each A and B is independently an unsubstituted or substitutedaromatic hydrocarbyl ring.
 25. A composition according to claim 1wherein each A and B is independently an unsubstituted or substitutedaromatic carbon ring.
 26. A composition according to claim 1 wherein oneor more of A and/or one or more of B is substituted with one or moresubstituents selected from alkyl, aryl, arylalkyl and alkaryl groups.27. A composition according to claim 1 wherein one or more of A and/orone or more of B is substituted with one or more alkyl groups,preferably one or more C₁₋₄ alkyl groups.
 28. A composition according toclaim 1 wherein each A and B is unsubstituted.
 29. A compositionaccording to claim 1 wherein each A and B is the same.
 30. A compositionaccording to claim 1 wherein each A and B is cyclopentadienyl.
 31. Acomposition according to claim 1 wherein n is 0, 1 or
 2. 32. Acomposition according to claim 1 wherein n is
 0. 33. A compositionaccording to claim 1 wherein the one or more compounds of formula (I)are selected from compounds of formula (IV):

wherein p is an integer from 4 to
 18. 34. A composition according toclaim 33 wherein p is an integer from 5 to
 10. 35. A compositionaccording to claim 33 wherein p is
 5. 36. A composition according toclaim 33 wherein p is 6 or
 7. 37. A composition according to claim 1wherein the one or more compound of formula (I) is present in an amountsufficient to provide, at −30° C., at least 4.0 wt % of iron, based onthe weight of the composition.
 38. A composition according to claim 1wherein the one or more compound of formula (I) is present in an amountsufficient to provide, at −30° C., at least 5.0 wt % of iron, based onthe weight of the composition.
 39. A fuel additive dosing apparatuscomprising: (a) a supply container formed from a plastics materialincompatible with an aromatic diluent or carrier; and (b) a composition,contained within the supply container comprising: i) at least onecompound of formula (I):

wherein R₁ and R₂ are independently selected from a group consisting ofhydrogen, unsubstituted or substituted C₁₋₁₉ hydrocarbyl or a group offormula (II):

wherein Q is a bond or an unsubstituted or substituted hydrocarbylgroup; wherein R₃ is selected from a group consisting of hydrogen andunsubstituted or substituted C₁₋₁₈ hydrocarbyl; wherein the R₁—C—R₂backbone is from 5 to 20 atoms in length; wherein each A and B isindependently an unsubstituted or substituted unsaturated cyclichydrocarbyl group; and wherein n is an integer from 0 to 10; and ii) alow aromatic or non-aromatic diluent or carrier; wherein the compound(s)of formula (I) is present in the composition in an amount sufficient toprovide, at −30° C., at least 1 wt % of iron, based on the weight of thecomposition.
 40. A fuel dosing apparatus according to claim 39 whereinthe supply container is formed from HDPE.
 41. A method of regenerating aparticulate filter located in an exhaust system of a combustion systemfor fuel, which comprises contacting carbon-based particulates, presentin the particulate filter, with combustion products of a compositioncomprising a compound of formula (I):

wherein R₁ and R₂ are independently selected from a group consisting ofhydrogen, unsubstituted or substituted C₁₋₁₉ hydrocarbyl or a groupselected of formula (II):

wherein Q is a bound or an unsubstituted or substituted hydrocarbylgroup; wherein R₃ is selected from a group consisting of hydrogen andunsubstituted or substituted C₁₋₁₈ hydrocarbyl; wherein the R₁—C—R₂backbone is from 5 to 20 atoms in length; wherein each A and B isindependently an unsubstituted or substituted unsaturated cyclichydrocarbyl group; and wherein the method comprises: (a) supplying thecomposition to a diesel fuel; (b) supplying the fuel containing thecomposition to a combustion system; and (c) combusting the fuel.
 42. Amethod according to claim 41, wherein the composition is located in acontainer associated with the combustion system for introduction intofuel prior to combustion of the fuel in the combustion system.
 43. Acomposition according to claim 1 wherein the composition is used for theregeneration of diesel particulate filter systems.
 44. A fuel additivedosing apparatus according to claim 39 wherein the composition is forthe regeneration of diesel particulate filter systems.
 45. A compositionlocated in a container associated with the combustion system of a highcompression spontaneous ignition engine for introduction into dieselfuel prior to combustion of the fuel in the combustion system, thecomposition comprising: i) at least one compound of formula (I):

wherein R₁ and R₂ are independently selected from a group consisting ofhydrogen, unsubstituted or substituted C₁₋₁₉ hydrocarbyl or a group offormula (II):

wherein Q is a bond or an unsubstituted or substituted hydrocarbylgroup; wherein R₃ is selected from a group consisting of hydrogen andunsubstituted or substituted C₁₋₁₈ hydrocarbyl; wherein the R₁—C—R₂backbone is from 5 to 20 atoms in length; wherein each A and B isindependently an unsubstituted or substituted unsaturated cyclichydrocarbyl group; and wherein n is an integer from 0 to 10; and ii) adiluent or carrier; wherein the compound(s) of formula (I) is present inan amount sufficient to provide, at −40° C., at least 1 wt % of iron,based on the weight of the composition; and wherein substantially all ofthe compound(s) of formula (I) is dissolved in the diluent or carrier.